Tool and related methods and apparatus

ABSTRACT

A tool for use in abrading, honing, lapping or otherwise finishing or working the interior surface of a bore, aperture, cylinder or like work piece includes an abrading element dependently supported about a mandrel assembly. The abrading element has a longitudinal slit in order that the abrading element is radially expansible upon the outward application of force from within a longitudinal bore provided therethrough. The mandrel assembly includes a threaded rod upon which is formed a radially expansible arbor, which is formed by application over and about the threaded rod of one or more radially expansible, preferably cylindrical, bushings, which bushings are separated and bounded by a plurality of radially fixed, preferably spherical bushings. The mandrel assembly may also be used as an inside diameter mandrel for supporting a work piece undergoing a machining process.

RELATED APPLICATIONS

This application claims priority, as a continuation-in-part under 35 U.S.C. §120, to P.C.T. international patent application No. PCT/US11/41735 filed Jun. 24, 2011, which designates the United States of America and, in turn, claims priority to U.S. provisional patent application Ser. No. 61/398,469 filed Jun. 25, 2010, the benefit of which is also claimed in this present application. By this reference, the full disclosures, including the drawings, claims and abstracts, of P.C.T. international patent application No. PCT/US11/41735 and U.S. provisional patent application Ser. No. 61/398,469 are incorporated herein as though each was now set forth in its respective entirety.

FIELD OF THE INVENTION

The present invention relates to abrading, honing, lapping or otherwise finishing or working the interior surface of a bore, aperture, cylinder or like work piece. More specifically, the present invention relates to a tool comprising a radially expansible hone, lap or like abrading element dependently mounted upon a mandrel, wherein the mandrel includes, among other features, provision for precisely controlling radial expansion of the supported abrading element. In a further application, however, the present invention also relates to use of the described mandrel for supporting work pieces during machining or like processes.

BACKGROUND OF THE INVENTION

Grinding and honing tools that can be adjusted to grind holes of different diameters have long been known and described in the art. For example, U.S. Pat. No. 2,694,277 issued Nov. 16, 1954 to Speck (“Speck”), which by this reference is incorporated herein as though now set forth in its entirety, shows and describes a tool comprising a shank having a stem portion (for dependent insertion into a greater machine adapted to impart rotational force to the tool) and a tapered portion for dependently receiving thereabout various types of grinding or cutting heads. As described in Speck, the grinding or cutting head takes the general form of a sleeve having a tapered hole therethrough, the provided tapered hole being sized and shaped to generally conform to the tapered portion of the shank. Additionally, the sleeve is longitudinally slit, thereby permitting its radial expansion and contraction as it is slidingly engaged more or less about the shank.

Although U.S. Pat. No. 3,526,057 issued Sep. 1, 1970 to Hackman (“Hackman”), which by this reference is incorporated herein as though now set forth in its entirety, shows and describes a slightly more complex tool, Hackman nonetheless concerns a tool generally devised about the same manner of adjustment as described nearly twenty years earlier by Speck. In fact, the mode of adjustment described by Speck is to this day still incorporated generally without change or improvement into tools that are manufactured by such well known tool companies as Engis Corporation of Wheeling, Ill. and its subsidiary Helical Lap & Mfg. Company of Fraser, Mich.

Unfortunately, however, such tools are subject to much criticism, beginning with the very high manufacturing cost associated with providing the required matching internal and external tapers, which tapers must be manufactured to tight tolerances for tools intended for precision applications. Additionally, and regardless of the quality of manufacture, the described arrangement is generally considered to be challenging in practice due to the difficulty in achieving the precise longitudinal position required to ultimately obtain a desired tool diameter. Further, because the grinding or cutting sleeves of such tools are frictionally engaged about their supporting shanks, they are highly subject to inadvertent longitudinal movement during use, which of course results in an incorrect diameter tool being applied to a work piece. Further still, extreme care must be taken in the use of such tools to ensure that only modest engagement be had between the grinding or cutting surfaces and the work piece as excessive contact can easily cause rotation of the sleeve about the shank, which in turn will almost always result in longitudinal displacement of the sleeve due to the concomitant relief in frictional engagement about the shank.

With the forgoing disadvantages of the prior art clearly in mind, it is an overriding object of the present invention to improve over the prior art by providing a tool comprising a radially expansible hone, lap or like abrading element dependently mounted upon a mandrel, wherein the mandrel includes, among other features, provision for precisely controlling radial expansion of the supported abrading element. Additionally, it is an object of the present invention to provide such a tool that is readily and economically manufactured and that is easy to employ in use. Still further, it is an object of the present invention to provide such a mandrel that may also be employed in related uses and, in particular, as an inside diameter type support for a work piece undergoing a machining or like process or operation.

SUMMARY OF THE INVENTION

In accordance with the foregoing objects, the present invention—a tool for use in abrading, honing, lapping or otherwise finishing or working the interior surface of a bore, aperture, cylinder or like work piece, and related methods, apparatus and uses—generally comprises an abrading element dependently supported on and about a mandrel assembly. The abrading element generally comprises one or more operable surfaces which may if desired be separated by one or more helically or otherwise arranged flutes, and a longitudinal slit in order that the abrading element is radially expansible upon the outward application of force from within a longitudinal bore provided therethrough.

The mandrel assembly of the present invention generally comprises a threaded rod upon which is formed in use a radially expansible arbor. The radially expansible arbor according to the present invention is preferably formed by application over and about the threaded rod of one or more radially expansible, preferably cylindrical, bushings, which bushings are separated and bounded by a plurality of radially fixed, preferably spherical bushings, also applied over and about the threaded rod. By tightening an adjustment nut on the threaded rod, the interior end of the adjustment nut is pressed against the adjacent radially fixed bushing while the opposite-most radially fixed bushing is stopped against the interior end of a chucking collar. The edges of the radially fixed bushings thus press into the interior spaces of the radially expansible bushings causing the whole of the radially expansible arbor to press outwardly against the longitudinal bore of the abrading element, causing radial expansion thereof, while the subsequent loosening of the adjustment nut results in the opposite contracting effect.

In a related use of the mandrel assembly comprising, as previously described, a radially expansible arbor formed thereon, the mandrel is fitted into a bore or the like in or through a work piece set to undergo a machining or like process. In this use, tightening of the adjustment nut serves to radially expand the arbor formed on and about the rod of the mandrel in order to secure the mandrel in place within the bore or like opening in or through the work piece. With the work piece thus firmly and dependently affixed to the mandrel (which, as will be appreciated by those of ordinary skill in the art, is in the described configuration acting as an “inside diameter” or “I.D.” mandrel), the work piece may be operated upon in the otherwise conventional fashion of the particular machining or like process to be applied.

Many other features, objects and advantages of the present invention will be apparent to those of ordinary skill in the relevant arts, especially in light of the foregoing discussions and the following drawings, exemplary detailed description and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Although the scope of the present invention is much broader than any particular embodiment, a detailed description of the preferred embodiment follows together with illustrative figures, wherein like reference numerals refer to like components, and wherein:

FIG. 1 shows, in a partially exploded perspective view, the various constituent components of the most preferred embodiment of the tool of the present invention;

FIG. 2 shows, in a perspective view generally corresponding to the view of FIG. 1, the tool of FIG. 1 as generally configured for use in an abrading, honing, lapping or like application;

FIG. 3 shows, in a top plan view, the tool of FIG. 1 as assembled in FIG. 2;

FIG. 4 shows, in a cross-sectional view taken through cut line 4-4 of FIG. 3, the tool of FIG. 1;

FIG. 5 shows, in a detail view identified in FIG. 4 with the reference numeral 5, aspects of the operation of the tool of FIG. 1;

FIG. 6 shows, in a detail view generally corresponding to the view of FIG. 5, an alternate implementation of various features of the tool of FIG. 1;

FIG. 7 shows, in the partially exploded perspective view of FIG. 1, the various constituent components of an alternatively preferred embodiment of the tool of the present invention;

FIG. 8 shows, in a partially exploded perspective view generally corresponding to that of FIG. 1, the various constituent components of a further alternatively preferred embodiment of the tool of the present invention;

FIG. 9 shows, in a perspective view generally corresponding to the view of FIG. 8, the tool of FIG. 8 as generally configured for use in an abrading, honing, lapping or like application;

FIG. 10 shows, in a front elevational view, the tool of FIG. 8 as assembled in FIG. 9;

FIG. 11 shows, in a cross-sectional view taken through cut line 11-11 of FIG. 9, the tool of FIG. 8;

FIG. 12, shows, in a cross-sectional view generally corresponding to the cross section of FIG. 11, details of an alternative embodiment of the chucking collar of the present invention;

FIG. 13 shows, in a detail view identified in FIG. 10 with the reference numeral 13, aspects of the preferred manufacture of the interface between the chucking collar and industrial abrading element of the present invention;

FIG. 14 shows, in a partially cut away front elevational view, details of the assembly of FIG. 9;

FIG. 15 shows, in a partially cut away front elevational view, details of an alternate assembly of the present invention;

FIG. 16 shows, in a schematic representation, details of the industrial abrading element profile as generally attained through the assembly of FIG. 15;

FIG. 17 shows, in a partially cut away front elevational view, details of a further alternate assembly of the present invention;

FIG. 18 shows, in a schematic representation, details of the industrial abrading element profile as generally attained through the assembly of FIG. 17;

FIG. 19 shows, in a partially cut away front elevational view, details of a still further alternate assembly of the present invention;

FIG. 20 shows, in a schematic representation, details of the industrial abrading element profile as generally attained through the assembly of FIG. 19;

FIG. 21 shows, in a partially cut away front elevational view, details of a still further alternate assembly of the present invention; and

FIG. 22 shows, in a schematic representation, details of the industrial abrading element profile as generally attained through the assembly of FIG. 21.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although those of ordinary skill in the art will readily recognize many alternative embodiments, especially in light of the illustrations provided herein, this detailed description is exemplary of the preferred embodiment of the present invention, the scope of which is limited only by the claims appended hereto.

As used herein, the term “abrading element” is expressly defined to broadly include all manner of abrading, honing, lapping, finishing and like elements as are generally used in the working of the interior surface of bores, apertures, cylinders or like work pieces, whether or not the operable surface or surfaces of any particular such element results in abrading, cutting, grinding, polishing, wearing or the like of the work piece and whether or not the operable element is integrally formed or dependent upon the external application of abrasive compound, polishing compound or the like.

While an abrading element as herein defined may be manufactured of any of a wide variety of materials, the present invention is particularly directed toward the needs of the industrial community. With this in mind, the present invention is particularly provided with features such that the invention is suitable for use with abrading elements manufactured of hardened metals such as, for example, spring steel or a substantial equivalent thereof such as, for example, cast iron material with memory. As used herein, the term “industrial abrading element” is expressly defined to mean an abrading element (as otherwise previously defined) that is manufactured from a hardened metal.

Referring now to the figures, and to FIGS. 1 and 2 in particular, and with the foregoing in mind, the preferred embodiment of the tool 10 of the present invention is shown to generally comprise an industrial abrading element 11 dependently supported on and about a mandrel assembly 18. As shown in the figures, and as is otherwise conventional in the art, the industrial abrading element 11 generally comprises one or more operable surfaces 12 which may if desired be separated by one or more helically or otherwise arranged flutes 13. As also is otherwise conventional in the art, the industrial abrading element 11 of the present invention further comprises a longitudinal slit 14 in order that the industrial abrading element 11, which most preferably is manufactured of spring steel, is radially expansible upon the outward application of force from within a longitudinal bore 15 provided therethrough. Contrary, however, to the longstanding teaching of the prior art, the provided longitudinal bore 15 through the industrial abrading element 11 takes a generally cylindrical form as opposed to the tapered bores typical of the prior art.

As particularly shown in FIG. 1, the mandrel assembly 18 of the present invention generally comprises a threaded rod 19, having an ordinary generally cylindrical form (as opposed to the complicated tapered structures of a prior art arbor) upon which is formed in use a radially expansible arbor 25. In particular, and as will be better understood further herein, the radially expansible arbor 25 according to the present invention is preferably formed by application over and about the threaded rod 19 of one or more radially expansible, preferably cylindrical, bushings 26, which bushings 26 are separated and bounded by a plurality of radially fixed, preferably spherical bushings 31, which bushings 31 are also applied over and about the threaded rod 19. In any case, the radially expansible arbor 25 is during setup of the tool 10 loosely sandwiched in place on the threaded rod 19 by and between a provided chucking collar 20 on one end and a provided preferably elongate adjustment nut 35 on the opposite end, whereafter the abrading element 11 is positioned over and about the loosely formed radially expansible arbor 25, as particularly shown in FIGS. 2 and 3.

Referring now to FIGS. 4 through 6, it is noted that in a critical aspect of the present invention the edges 32 of the radially fixed bushings 31 are exteriorly oriented such that they project into and within the space bounded by the interiorly oriented edges 28 of the adjacent radially expansible bushings 26. In this manner, the radially fixed bushings 31 are adapted to cause expansion of the radially expansible bushings 26 when pressed against the edges 28 of the expansible bushings 26, which are provided for this purpose with a longitudinal slit 27. Additionally, in an aspect of the present invention that is very important for obtaining optimal performance during this operation, it is noted that the interface between the edges 28 of the radially expansible bushings 26 and the edges 32 of the radially fixed bushings 31 should in all cases be formed so as to avoid excessive friction between the edges 28, 32 such as may result from the sandwiching of one substantially straight edge together with another substantially straight edge. To this end, as shown in the figures, the interface between the edges 28 of the radially expansible bushings 26 and the edges 32 of the radially fixed bushings 31 may be formed so as to result in a substantially straight edge engaging a generally convex edge. For example, as particularly shown in FIG. 5, the interiorly oriented edges 28 of the radially expansible bushings 26 may be formed with substantially straight chamfers 29 to present a flat bevel against the exteriorly oriented edges 32 of the radially fixed bushings 31 provided in convex form 33. Alternatively, as particularly shown in FIG. 6, the exteriorly oriented edges 32 of the radially fixed bushings 31 may be formed with substantially straight chamfers 34 to present a flat bevel against the interiorly oriented edges 28 of the radially expansible bushings 26 provided in convex form 30. Still further, however, it should also be recognized that other shapes and arrangements equally capable of obtaining the desired result will be readily within the ordinary skill in the art. For example, the edges 28 of the radially expansible bushings 26 and the edges 32 of the radially fixed bushings 31 may all be formed as convex curves.

In any case, with the basic structure of the present invention described, those of ordinary skill in the art will recognize that by tightening the adjustment nut 35 on the threaded rod 19, the interior end 36 of the adjustment nut 35 will press against the adjacent radially fixed bushing 31 while the opposite-most radially fixed bushing 31 is stopped against the interior end 23 of the chucking collar 20, in turn causing the edges 28 of the radially fixed bushings 31 to press into the interior spaces of the radially expansible bushings 26 and thereby causing the whole of the radially expansible arbor 25 to press outwardly against the longitudinal bore 15 of the industrial abrading element 11, which finally will thereby be itself radially expanded. Likewise, those of ordinary skill in the art will recognize that the subsequent loosening of the adjustment nut 35 will result in the opposite contracting effect.

In a critical aspect of the present invention as implemented comprising, or adapted for use with, an industrial abrading element 11, the radially expansible bushings 26 and the radially fixed bushings 31 must be manufactured from a material suitable for withstanding the high operating forces required to cause expansion of an industrial abrading element 11. To this end, Applicant has found it suitable for the widest variety of industrial applications to manufacture the radially expansible bushings 26 from spring steel having a Rockwell scale C hardness (“HRC”) of approximately 40 and to manufacture and the radially fixed bushings 31 from steel having an HRC of approximately 60. As used herein, the term “hardened” as used in connection with either the radially expansible bushings 26 or the radially fixed bushings 31 of the present invention shall mean that the referred to bushings 26, 31 are manufactured from a material having an HRC of at least 20.

In order to ensure positive position of the chucking collar 20, the chucking collar 20 may be provided with a longitudinal slit 21 such that the tapped bore 22 through the chucking collar 20 is clamped into place about the threaded rod 19 as the chucking collar 20 is accepted into a machine collet or the like. In this manner, as will be appreciated by those of ordinary skill in the art, the chucking collar 20 may be rotationally fixed in place about the threaded rod 19 such that the chucking collar 20 is positively prevented from screwing in either direction along the threaded rod 19.

Additionally, in order to prevent inadvertent turning of the abrading element 11 with respect to the mandrel assembly 18, the chucking collar 20 may be and is preferably provided with one or more milled or otherwise formed tangs 24. As particularly shown in FIGS. 1 through 3, the provided tangs 24 are adapted to positively engage with slots 17 provided on one or both ends 16 of the industrial abrading element 11. In this manner, as will be understood by those of ordinary skill in the art, the abrading element 11 may be rotationally fixed with the chucking collar 20, which itself may be rotationally fixed as discussed in the foregoing paragraph.

Still further, it is noted that the otherwise described threaded rod 19 may be formed, as particularly shown in FIG. 7, to be threaded only adjacent the ends thereof, leaving a smooth central portion 37 upon which the radially fixed bushings 31 may more freely slide.

Referring now to FIGS. 8 through 22, in particular, alternative implementations of the present invention are shown to comprise (1) the provision of one or more spacer elements 38, (2) the provision of a plurality of radially expansible bushings 26 wherein individual bushings are manufactured to comprise differing mechanical properties or (3) a combination of such provisions. As shown in FIG. 8, one or more spacer elements 38 may be placed and about the threaded rod 19 in the manner as would otherwise be placed a radially expansible bushing 26. As will be appreciated by those of ordinary skill in the art in light of this exemplary description, placement of such a spacer element 38 provides a region of no expansion within the otherwise radially extensible arbor 25. As shown in FIG. 8, a suitable spacer may be manufactured in identical form as is manufactured a radially expansible bushing 26 with the exception that no longitudinal slit 27 will be provided for a spacer element 38. It is noted, however, that the spacer element 38 must, like the radially expansible bushings 26, be hardened. Additionally, it is noted that a spacer element 38 according to the present invention may comprise square edges or chamfered or curved edges as also described with respect to the radially expansible bushings.

As particularly shown in FIGS. 8 through 11, a tool 18 comprising spacer elements 38 is generally assembled in same the manner as previously described in detail with the exception of the introduction to the “sandwich” of the spacer elements 38. As shown in FIG. 14, one implementation making use of the spacer elements 38 comprises the provision of the one spacer element 38 at each distal end of the radially extensible arbor 25, which, it has been discovered, generally prevents binding at the end of the industrial abrading element 11 as the radially extensible arbor 25 expands or contracts. Additionally, a profile such as the profile depicted in FIG. 16 may be achieved with the setup of FIG. 15, where a spacer element 38 in inserted between radially expansible bushings 26.

In the second alternative implementation of the present invention, however, a plurality of radially expansible bushings 26 manufactured to comprise differing mechanical properties may be utilized in the “sandwich.” As shown in the figures, such radially expansible bushings 26 look essentially the same as previously described and are manufactured in identical manner with the exception that the wall thicknesses of these bushings 26 are made to have slight variance one from another. Because only slight variance is necessary to affect the manner in which the present invention operates, however, the bushings 26 are preferably provided with external indicia, such as, for example, the circumferential grooves shown in the figures, thereby enabling the user of the tool 10 to readily distinguish one from another.

In the examples following, four “thicknesses” of radially expansible bushings 26 are shown. In particular, a radially expansible bushing 26 having the thickest wall is shown as marked with four grooves 44 while a radially expansible bushing 26 having the thinnest wall is shown as marked with a single grooves 43. Intermediate thicknesses are shown as being marked with three grooves 45 and two grooves 46. In any case, in use the thicker radially expansible bushings 26 will generally slower and to a lesser degree than will the thinner radially expansible bushings 26. In this manner, the radially expansible bushings 26 of varying wall thickness may be utilize with or without spacer elements 38 to effect very precise yet complex profiles for the industrial abrading element 11. For example, a generally strait chamfer profile as depicted in FIG. 18 may be effected with a setup like that shown in FIG. 17, a generally concave profile as depicted in FIG. 20 may be effected with a setup like that shown in FIG. 19 or a generally convex profile as depicted in FIG. 22 may be effected with a setup like that shown in FIG. 21. Additionally, other profiles may in like manner be effected generally without limit.

Finally, as has been previously discussed, it is noted that the novel and inventive mandrel assembly 18 of the present invention may be put to use in applications beyond its use in forming a tool 10 for use in abrading, honing, lapping or otherwise finishing or working the interior surface of a bore, aperture, cylinder or like work piece. For example, the mandrel assembly 18 formed with radially expansible arbor 25 (as previously described in detail) may be used as an inside diameter mandrel, such as is useful for dependently supporting a work piece undergoing any of a wide variety of machining or like processes such as, for example, working with a CNC machine, a lathe or a like machine as are well known to those of ordinary skill in the art. In such an application, the mandrel assembly 18 with radially expansible arbor 25 formed thereon is fitted into a bore or the like in or through a work piece set to undergo the machining or like process. As will be appreciated by those of ordinary skill in the art in light of the foregoing discussions, tightening of the adjustment nut 35 serves to radially expand the arbor 25 formed on and about the rod 19 of the mandrel assembly 18 in order to secure the mandrel assembly 18 in place within the bore or like opening in or through the work piece. With the work piece thus firmly and dependently affixed to the mandrel assembly 18, the work piece may be operated upon in the otherwise conventional fashion of the particular machining or like process to be applied.

While the foregoing description is exemplary of the preferred embodiment of the present invention, those of ordinary skill in the relevant arts will recognize the many variations, alterations, modifications, substitutions and the like as are readily possible, especially in light of this description, the accompanying drawings and the claims drawn hereto. For example, as generally shown in FIG. 12, the chucking collar 20 may be formed without provision of a longitudinal slit 21 and the bore 40 through the chucking collar 20 may comprise a combination of threaded portion 41 and smooth portion 42 such as will generally closely accept a threaded rod 19 also having a smooth portion 37.

Additionally, Applicant has found that the tangs 24 provided in connection with the chucking collar 20 are preferably sized slightly smaller than the slots 17 formed in the ends 16 of the industrial abrading element 11. In this manner binding and the like is avoided. In any case, because the scope of the present invention is much broader than any particular embodiment, the foregoing detailed description should not be construed as a limitation of the present invention, which is limited only by the claims appended hereto. 

1. An abrading tool, said abrading tool comprising: a mandrel assembly, said mandrel assembly comprising: a generally cylindrical rod, said rod having at a first end thereof a stop and having at an opposite, second end thereof an adjustment; a radially expansible arbor, said radially expansible arbor being dependently positioned about said rod between said stop and said adjustment; and wherein said adjustment is operable to cause radial expansion of said radially expansible arbor; and an industrial abrading element, wherein: said industrial abrading element comprises a substantially cylindrical longitudinal bore therethrough, said bore being adapted for sliding engagement over and about said radially expansible arbor; said industrial abrading element is dependently supported about said mandrel assembly and radially expansible under radial expansion of said radially expansible arbor.
 2. The abrading tool as recited in claim 1, wherein said radially expansible arbor comprises: a radially expansible hardened bushing, said radially expansible hardened bushing being slidingly engaged about said rod; a plurality of radially fixed hardened bushings, said radially fixed hardened bushings being slidingly engaged about said rod; and wherein said radially fixed hardened bushings bound said radially expansible hardened bushing.
 3. The abrading tool as recited in claim 1, wherein said radially expansible arbor comprises: a plurality of radially expansible hardened bushings, said radially expansible hardened bushings being slidingly engaged about said rod; a plurality of radially fixed hardened bushings, said radially fixed hardened bushings being slidingly engaged about said rod; and wherein said radially fixed hardened bushings separate and bound said radially expansible hardened bushings.
 4. The abrading tool as recited in claim 3, wherein: each said radially expansible hardened bushing is generally cylindrical and comprises a longitudinal slit therethrough; and each said radially fixed hardened bushing is generally spherical.
 5. The abrading tool as recited in claim 4, wherein said stop comprises a chucking collar.
 6. The abrading tool as recited in claim 5, wherein: said rod is threaded at said first end; and said chucking collar is adapted for threaded engagement with said threaded first end of said rod.
 7. The abrading tool as recited in claim 6, wherein: said chucking collar comprises a tang; and said industrial abrading element comprises a slot, said slot being sized and positioned on said industrial abrading element for mating engagement with said tang of said chucking collar.
 8. The abrading tool as recited in claim 6, wherein: said rod is threaded at said second end; and said adjustment comprises a nut adapted for threaded engagement with said threaded second end of said rod.
 9. A mandrel assembly for use with an industrial abrading element, said mandrel assembly comprising: a generally cylindrical rod, said rod having at a first end thereof a stop and having at an opposite, second end thereof an adjustment; a radially expansible arbor, said radially expansible arbor being dependently positioned about said rod between said stop and said adjustment and comprising: a radially expansible hardened bushing, said radially expansible hardened bushing being slidingly engaged about said rod; a plurality of radially fixed hardened bushings, said radially fixed hardened bushings being slidingly engaged about said rod; and wherein said radially fixed hardened bushings bound said radially expansible hardened bushing; and wherein said adjustment is operable to cause radial expansion of said radially expansible arbor.
 10. The mandrel assembly as recited in claim 9, wherein said stop comprises a chucking collar.
 11. The mandrel assembly as recited in claim 10, wherein: said rod is threaded at said first end; and said chucking collar is adapted for threaded engagement with said threaded first end of said rod.
 12. A mandrel assembly for use with an industrial abrading element, said mandrel assembly comprising: a generally cylindrical rod, said rod having at a first end thereof a stop and having at an opposite, second end thereof an adjustment; a radially expansible arbor, said radially expansible arbor being dependently positioned about said rod between said stop and said adjustment and comprising: a plurality of radially expansible hardened bushings, said radially expansible hardened bushings being slidingly engaged about said rod; a plurality of radially fixed hardened bushings, said radially fixed hardened bushings being slidingly engaged about said rod; and wherein said radially fixed hardened bushings bound said radially expansible hardened bushings; and wherein said adjustment is operable to cause radial expansion of said radially expansible arbor.
 13. The mandrel assembly as recited in claim 12, wherein: said rod is threaded at said second end; and said adjustment comprises a nut adapted for threaded engagement with said threaded second end of said rod.
 14. The mandrel assembly as recited in claim 13, wherein said stop comprises a chucking collar.
 15. The mandrel assembly as recited in claim 12, wherein said stop comprises a chucking collar.
 16. The mandrel assembly as recited in claim 12, wherein at least one of said plurality of radially expansible hardened bushings comprises a wall thickness greater than the wall thickness of at least one other of said plurality of radially expansible hardened bushings.
 17. The mandrel assembly as recited in claim 16, wherein said radially expansible arbor further comprises a spacer element.
 18. The mandrel assembly as recited in claim 12, wherein said radially expansible arbor further comprises a spacer element. 